Texas Gov. Greg Abbott called the shooting “one of the most heinous attacks that we’ve ever seen in the history of Texas schools,” and described the suspect, 17-year-old Dimitrios Pagourtzis, as “evil.”

The Santa Fe High School shooting comes just months after another massacre at Marjory Stoneman Douglas High School in February, in which 17 people were killed in Parkland, Florida. That shooting, as have many others, reignited a nationwide discussion over gun rights and gun control.

Here’s a timeline of how the attack in Santa Fe, Texas, unfolded on Friday:

7:32 a.m: Law enforcement agencies respond to an active-shooter situation at Santa Fe High School in Santa Fe, Texas

7:45 a.m. to 8:00 a.m: Police arrive on the scene. Neighbouring schools are also placed on lockdown

Harris County Sheriff’s OfficeLaw enforcement officers respond to the Santa Fe High School shooting in Santa Fe, Texas, May 18, 2018.

We’re currently in protect mode as a precaution because of reports of a shooting at Santa Fe HS. Doors are locked & personnel are stationed at outer doors to let people in and out. No students allowed outside of building. Field trips are postponed until we go off of protect mode.

9:15 a.m: Suspected explosive devices are discovered

#UPDATE Possible explosive devices have been located at the school and off campus. Law enforcement is in the process of rendering them safe. School has been evacuated. Call 911 if you see any suspicious item. #HouNews#SantaFeISD